The meaning and practice of stewardship in South Africa
- Cockburn, Jessica J, Cundill, Georgina, Shackleton, Sheona E, Rouget, Mathieu
- Authors: Cockburn, Jessica J , Cundill, Georgina , Shackleton, Sheona E , Rouget, Mathieu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390683 , vital:68574 , xlink:href="http://dx.doi.org/10.17159/sajs.2019/5339"
- Description: Stewardship offers a means of addressing social-ecological sustainability challenges, from the local to the global level. The concept of stewardship has had various meanings attached to it over time, and the links between the theory and practice of stewardship are not well understood. We sought to characterise the practice of stewardship in South Africa, to better understand the relationship between theory and practice. We found that practitioners’ understandings of stewardship coalesce around two core notions: the idea of stewardship as ‘responsible use and care’ of nature, and stewardship as a ‘balancing act’ between stewards’ use of natural resources for agricultural production and their responsibility to protect and manage the wider ecosystem. Stewardship practice in South Africa is strongly influenced by the biodiversity stewardship tool; however, many practitioners are integrating biodiversity stewardship with other approaches. These emerging social-ecological stewardship initiatives operate at landscape-level and work towards integrated social and ecological stewardship outcomes, by facilitating collaboration among diverse stakeholders. Further research is needed to better understand what is required to support these integrated, collaborative and cross-sectoral initiatives. Policy mechanisms that facilitate integrated place-based stewardship practice can contribute to expanding the practice of biodiversity stewardship in South Africa.
- Full Text:
- Authors: Cockburn, Jessica J , Cundill, Georgina , Shackleton, Sheona E , Rouget, Mathieu
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390683 , vital:68574 , xlink:href="http://dx.doi.org/10.17159/sajs.2019/5339"
- Description: Stewardship offers a means of addressing social-ecological sustainability challenges, from the local to the global level. The concept of stewardship has had various meanings attached to it over time, and the links between the theory and practice of stewardship are not well understood. We sought to characterise the practice of stewardship in South Africa, to better understand the relationship between theory and practice. We found that practitioners’ understandings of stewardship coalesce around two core notions: the idea of stewardship as ‘responsible use and care’ of nature, and stewardship as a ‘balancing act’ between stewards’ use of natural resources for agricultural production and their responsibility to protect and manage the wider ecosystem. Stewardship practice in South Africa is strongly influenced by the biodiversity stewardship tool; however, many practitioners are integrating biodiversity stewardship with other approaches. These emerging social-ecological stewardship initiatives operate at landscape-level and work towards integrated social and ecological stewardship outcomes, by facilitating collaboration among diverse stakeholders. Further research is needed to better understand what is required to support these integrated, collaborative and cross-sectoral initiatives. Policy mechanisms that facilitate integrated place-based stewardship practice can contribute to expanding the practice of biodiversity stewardship in South Africa.
- Full Text:
The role of invasive alien species in shaping local livelihoods and human well-being: A review
- Shackleton, Ross T, Shackleton, Charlie M, Kull, Christian A
- Authors: Shackleton, Ross T , Shackleton, Charlie M , Kull, Christian A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180280 , vital:43349 , xlink:href="https://doi.org/10.1016/j.jenvman.2018.05.007"
- Description: Invasive alien species are a well-recognised driver of social-ecological change globally. Much research has focused on ecological impacts, but the role of invasive species for livelihoods and human well-being is less well known. Understanding the effects (benefits and costs) of invasive species on livelihoods and human well-being is important for guiding policy formulation and management. Here we review the literature on the role of invasive species in livelihoods to assess what is known, identify knowledge gaps and provide recommendations for future research. Literature was collected using key word searches and included both journal publications and grey literature. Slightly less than half (48%) of species studied had both substantial positive and negative impacts on local livelihoods (e.g. Australian Acacia spp. species; Camelus dromedaries; Lantana camara; Prosopis spp.), with 37% inducing mainly costs (Chromolaena odorata; Lissachatina fulica; Opuntia stricta) and 16% producing mainly benefits (Opuntia ficus-indica; Acacia spp.). Some species, such as Acacia dealbata, fell into different categories depending on the social-ecological context. Key benefits or services included the provision of fuelwood, fodder, timber and food products for local households communities and to a lesser extent supporting and regulating services such as soil improvement and shade. A number of species also provided cultural services such as recreation and spiritual values and provided many with an opportunity to earn a cash income. However, invasive species also harm livelihoods and increase vulnerability through encroaching on land and reducing mobility or access. They can also decrease the supply of natural resources used by households and reduce agricultural production (livestock and/or crops) which can result in losses of income and increased vulnerability. Furthermore, some invasive species were seen to have negative implications for human health and safety and reduce the cultural value of landscapes. Economic impacts on livelihoods as a result of invasive species were highly variable and very dependent on the social-ecological contexts. These negative implications can reduce resilience and adaptive capacity of households and communities thus increasing their vulnerability to change. Drawing on case studies we highlight that efforts for managing invasive species need to safeguard livelihood benefits while mitigating negative impacts. In concluding we highlight future research and policy needs on the topic of invasive species, livelihoods and human well-being.
- Full Text:
- Authors: Shackleton, Ross T , Shackleton, Charlie M , Kull, Christian A
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180280 , vital:43349 , xlink:href="https://doi.org/10.1016/j.jenvman.2018.05.007"
- Description: Invasive alien species are a well-recognised driver of social-ecological change globally. Much research has focused on ecological impacts, but the role of invasive species for livelihoods and human well-being is less well known. Understanding the effects (benefits and costs) of invasive species on livelihoods and human well-being is important for guiding policy formulation and management. Here we review the literature on the role of invasive species in livelihoods to assess what is known, identify knowledge gaps and provide recommendations for future research. Literature was collected using key word searches and included both journal publications and grey literature. Slightly less than half (48%) of species studied had both substantial positive and negative impacts on local livelihoods (e.g. Australian Acacia spp. species; Camelus dromedaries; Lantana camara; Prosopis spp.), with 37% inducing mainly costs (Chromolaena odorata; Lissachatina fulica; Opuntia stricta) and 16% producing mainly benefits (Opuntia ficus-indica; Acacia spp.). Some species, such as Acacia dealbata, fell into different categories depending on the social-ecological context. Key benefits or services included the provision of fuelwood, fodder, timber and food products for local households communities and to a lesser extent supporting and regulating services such as soil improvement and shade. A number of species also provided cultural services such as recreation and spiritual values and provided many with an opportunity to earn a cash income. However, invasive species also harm livelihoods and increase vulnerability through encroaching on land and reducing mobility or access. They can also decrease the supply of natural resources used by households and reduce agricultural production (livestock and/or crops) which can result in losses of income and increased vulnerability. Furthermore, some invasive species were seen to have negative implications for human health and safety and reduce the cultural value of landscapes. Economic impacts on livelihoods as a result of invasive species were highly variable and very dependent on the social-ecological contexts. These negative implications can reduce resilience and adaptive capacity of households and communities thus increasing their vulnerability to change. Drawing on case studies we highlight that efforts for managing invasive species need to safeguard livelihood benefits while mitigating negative impacts. In concluding we highlight future research and policy needs on the topic of invasive species, livelihoods and human well-being.
- Full Text:
Effects of the carboxylic acid substituents on the photophysical and nonlinear optical properties of asymmetrical Zn (II) phthalocyanines–quantum dots conjugates
- Mgidlana, Sithi, Oluwole, David O, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187662 , vital:44684 , xlink:href="https://doi.org/10.1080/24701556.2018.1503684"
- Description: This work reports on three asymmetrical Zn(II) phthalocyanines, namely: zinc(II) 3–(4-phenoxy)propanoic acid) phthalocyanine(1), zinc(II) 3–(4-phenoxy carboxylic acid) phthalocyanine (2) and zinc(II) 3–(4–oxy)phenoxy)acetic acid phthalocyanine (3) when covalently linked to glutathione(GSH) capped CdTe/ZnSe and CdTe/ZnSe/ZnO quantum dots (QDs). Of the Pc complexes alone, 1 afforded the highest triplet quantum yield (ΦT) value of 0.67 with corresponding largest nonlinear absorption coefficient (βeff) value of 14.0 cm/GW compared to 2 and 3. The conjugates afforded improved triplet quantum yield and nonlinear optical behavior in comparison to the Pc complexes alone.
- Full Text:
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187662 , vital:44684 , xlink:href="https://doi.org/10.1080/24701556.2018.1503684"
- Description: This work reports on three asymmetrical Zn(II) phthalocyanines, namely: zinc(II) 3–(4-phenoxy)propanoic acid) phthalocyanine(1), zinc(II) 3–(4-phenoxy carboxylic acid) phthalocyanine (2) and zinc(II) 3–(4–oxy)phenoxy)acetic acid phthalocyanine (3) when covalently linked to glutathione(GSH) capped CdTe/ZnSe and CdTe/ZnSe/ZnO quantum dots (QDs). Of the Pc complexes alone, 1 afforded the highest triplet quantum yield (ΦT) value of 0.67 with corresponding largest nonlinear absorption coefficient (βeff) value of 14.0 cm/GW compared to 2 and 3. The conjugates afforded improved triplet quantum yield and nonlinear optical behavior in comparison to the Pc complexes alone.
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Exploring molecular insights into the interaction mechanism of cholesterol derivatives with the Mce4A: A combined spectroscopic and molecular dynamic simulation studies
- Khan, Shagufta, Khan, Faez I, Khan, Parvez, Hasan, Gulam M, Lobb, Kevin A, Islam, Asimul, Ahmad, Faizan, Hassan, M Imtaiyaz
- Authors: Khan, Shagufta , Khan, Faez I , Khan, Parvez , Hasan, Gulam M , Lobb, Kevin A , Islam, Asimul , Ahmad, Faizan , Hassan, M Imtaiyaz
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447041 , vital:74579 , xlink:href="https://doi.org/10.1016/j.ijbiomac.2017.12.160"
- Description: Mammalian cell entry protein (Mce4A) is a member of MCE-family, and is being considered as a potential drug target of Mycobacterium tuberculosis infection because it is required for invasion and latent survival of pathogen by utilizing host's cholesterol. In the present study, we performed molecular docking followed by 100 ns MD simulation studies to understand the mechanism of interaction of Mce4A to the cholesterol derivatives and probucol. The selected ligands, cholesterol, 25-hydroxycholesterol, 5-cholesten-3β-ol-7-one and probucol bind to the predicted active site cavity of Mce4A, and complexes remain stable during entire simulation of 100 ns. In silico studies were further validated by fluorescence-binding studies to calculate actual binding affinity and number of binding site(s). The non-toxicity of all ligands was confirmed on human monocytic cell (THP1) by MTT assay. This work provides a deeper insight into the mechanism of interaction of Mce4A to cholesterol derivatives, which may be further exploited to design potential and specific inhibitors to ameliorate the Mycobacterium pathogenesis.
- Full Text:
- Authors: Khan, Shagufta , Khan, Faez I , Khan, Parvez , Hasan, Gulam M , Lobb, Kevin A , Islam, Asimul , Ahmad, Faizan , Hassan, M Imtaiyaz
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447041 , vital:74579 , xlink:href="https://doi.org/10.1016/j.ijbiomac.2017.12.160"
- Description: Mammalian cell entry protein (Mce4A) is a member of MCE-family, and is being considered as a potential drug target of Mycobacterium tuberculosis infection because it is required for invasion and latent survival of pathogen by utilizing host's cholesterol. In the present study, we performed molecular docking followed by 100 ns MD simulation studies to understand the mechanism of interaction of Mce4A to the cholesterol derivatives and probucol. The selected ligands, cholesterol, 25-hydroxycholesterol, 5-cholesten-3β-ol-7-one and probucol bind to the predicted active site cavity of Mce4A, and complexes remain stable during entire simulation of 100 ns. In silico studies were further validated by fluorescence-binding studies to calculate actual binding affinity and number of binding site(s). The non-toxicity of all ligands was confirmed on human monocytic cell (THP1) by MTT assay. This work provides a deeper insight into the mechanism of interaction of Mce4A to cholesterol derivatives, which may be further exploited to design potential and specific inhibitors to ameliorate the Mycobacterium pathogenesis.
- Full Text:
Household food insecurity along an agro-ecological gradient influences children’s nutritional status in South Africa
- Chakona, Gamuchirai, Shackleton, Charlie M
- Authors: Chakona, Gamuchirai , Shackleton, Charlie M
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179836 , vital:43193 , xlink:href="https://doi.org/10.3389/fnut.2017.00072"
- Description: The burden of food insecurity and malnutrition is a severe problem experienced by many poor households and children under the age of five are at high risk. The objective of the study was to examine household food insecurity, dietary diversity, and child nutritional status in relation to local context which influences access to and ability to grow food in South Africa and explore the links and associations between these and household socio-economic status. Using a 48-h dietary recall method, we interviewed 554 women from randomly selected households along a rural–urban continuum in three towns situated along an agro-ecological gradient. The Household Dietary Diversity Scores (HDDS) and the Household Food Insecurity Access Scale (HFIAS) tools were used to measure household dietary diversity and food insecurity, respectively. Anthropometric measurements with 216 children (2–5 years) from the sampled households were conducted using height-for-age and mid-upper arm circumference (MUAC) as indicators of stunting and wasting, respectively. The key findings were that mean HDDS declined with decreasing agro-ecological potential from the wettest site (8.44 ± 1.72) to the other two drier sites (7.83 ± 1.59 and 7.76 ± 1.63). The mean HFIAS followed the opposite trend. Stunted growth was the dominant form of malnutrition detected in 35% of children and 18% of children were wasted. Child wasting was greatest at the site with lowest agro-ecological potential. Children from households with low HDDS had large MUAC which showed an inverse association among HDDS and obesity. Areas with agro-ecological potential had lower prevalence of food insecurity and wasting in children. Agro-ecological potential has significant influence on children’s nutritional status, which is also related to household food security and socio-economic status. Dependence on food purchasing and any limitations in households’ income, access to land and food, can result in different forms of malnutrition in children. Responses to address malnutrition in South Africa need to be prioritized and move beyond relying on food security and nutritional-specific interventions, but rather on nutrition-specific and sensitive programs and approaches; and building an enabling environment. Land availability, agriculture (including climate-smart agriculture especially in drier areas), and wild foods usage should be promoted.
- Full Text:
- Authors: Chakona, Gamuchirai , Shackleton, Charlie M
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179836 , vital:43193 , xlink:href="https://doi.org/10.3389/fnut.2017.00072"
- Description: The burden of food insecurity and malnutrition is a severe problem experienced by many poor households and children under the age of five are at high risk. The objective of the study was to examine household food insecurity, dietary diversity, and child nutritional status in relation to local context which influences access to and ability to grow food in South Africa and explore the links and associations between these and household socio-economic status. Using a 48-h dietary recall method, we interviewed 554 women from randomly selected households along a rural–urban continuum in three towns situated along an agro-ecological gradient. The Household Dietary Diversity Scores (HDDS) and the Household Food Insecurity Access Scale (HFIAS) tools were used to measure household dietary diversity and food insecurity, respectively. Anthropometric measurements with 216 children (2–5 years) from the sampled households were conducted using height-for-age and mid-upper arm circumference (MUAC) as indicators of stunting and wasting, respectively. The key findings were that mean HDDS declined with decreasing agro-ecological potential from the wettest site (8.44 ± 1.72) to the other two drier sites (7.83 ± 1.59 and 7.76 ± 1.63). The mean HFIAS followed the opposite trend. Stunted growth was the dominant form of malnutrition detected in 35% of children and 18% of children were wasted. Child wasting was greatest at the site with lowest agro-ecological potential. Children from households with low HDDS had large MUAC which showed an inverse association among HDDS and obesity. Areas with agro-ecological potential had lower prevalence of food insecurity and wasting in children. Agro-ecological potential has significant influence on children’s nutritional status, which is also related to household food security and socio-economic status. Dependence on food purchasing and any limitations in households’ income, access to land and food, can result in different forms of malnutrition in children. Responses to address malnutrition in South Africa need to be prioritized and move beyond relying on food security and nutritional-specific interventions, but rather on nutrition-specific and sensitive programs and approaches; and building an enabling environment. Land availability, agriculture (including climate-smart agriculture especially in drier areas), and wild foods usage should be promoted.
- Full Text:
Photophysical and strong optical limiting properties of ball-type phthalocyanines dimers and their monomeric analogues
- Nwaji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187930 , vital:44711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.10.045"
- Description: The nonlinear optical behaviors of ball-type phthalocyanine complexes: 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl))bis(phthalocyaninato zinc (II)] (5), 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl) bis(phthalocyaninato gallium (III) chloride)] (6), and 1′, 11,’15′,25′-tetrakis-4,4′-((4-formyl-1,2-phenoxyl)bis(phthalocyaninato indium (III) chloride)] (7) and the corresponding monomeric derivatives 8–10 were investigated using nanosecond pulse open aperture Z-scan technique at 532 nm. The nonlinear response showed strong reverse saturable absorption for all the complexes both in solution and when embedded in polymer matrix. The dimeric complexes showed better optical limiting properties compared to the monomeric derivatives. The βeff values for the dimeric complexes 5–7 were found to be 48.5, 55.2, and 60.1 cm/GW for 5, 6A, and 7 respectively, higher than the corresponding monomeric derivatives 8–10. Enhanced optical limiting properties were observed when the complexes were formulated in thin films. The second order hyperpolarizability values were in order of 10−28–10−26 esu in solution and 10−27–10−26 in films.
- Full Text:
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187930 , vital:44711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.10.045"
- Description: The nonlinear optical behaviors of ball-type phthalocyanine complexes: 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl))bis(phthalocyaninato zinc (II)] (5), 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl) bis(phthalocyaninato gallium (III) chloride)] (6), and 1′, 11,’15′,25′-tetrakis-4,4′-((4-formyl-1,2-phenoxyl)bis(phthalocyaninato indium (III) chloride)] (7) and the corresponding monomeric derivatives 8–10 were investigated using nanosecond pulse open aperture Z-scan technique at 532 nm. The nonlinear response showed strong reverse saturable absorption for all the complexes both in solution and when embedded in polymer matrix. The dimeric complexes showed better optical limiting properties compared to the monomeric derivatives. The βeff values for the dimeric complexes 5–7 were found to be 48.5, 55.2, and 60.1 cm/GW for 5, 6A, and 7 respectively, higher than the corresponding monomeric derivatives 8–10. Enhanced optical limiting properties were observed when the complexes were formulated in thin films. The second order hyperpolarizability values were in order of 10−28–10−26 esu in solution and 10−27–10−26 in films.
- Full Text:
Quantitation of zolpidem in biological fluids by electro-driven microextraction combined with HPLC-UV analysis
- Yaripour, Saeid, Mohammadi, Ali, Esfanjani, Isa, Walker, Roderick B, Nojavan, Saeed
- Authors: Yaripour, Saeid , Mohammadi, Ali , Esfanjani, Isa , Walker, Roderick B , Nojavan, Saeed
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184723 , vital:44266 , xlink:href="http://dx.doi.org/10.17179/excli2018-1140"
- Description: In this study, for the first time, an electro-driven microextraction method named electromembrane extraction combined with a simple high performance liquid chromatography and ultraviolet detection was developed and validated for the quantitation of zolpidem in biological samples. Parameters influencing electromembrane extraction were evaluated and optimized. The membrane consisted of 2-ethylhexanol immobilized in the pores of a hollow fiber. As a driving force, a 150 V electric field was applied to facilitate the analyte migration from the sample matrix to an acceptor solution through a supported liquid membrane. The pHs of donor and acceptor solutions were optimized to 6.0 and 2.0, respectively. The enrichment factor was obtained >75 within 15 minutes. The effect of carbon nanotubes (as solid nano-sorbents) on the membrane performance and EME efficiency was evaluated. The method was linear over the range of 10-1000 ng/mL for zolpidem (R2 >0.9991) with repeatability (%RSD) between 0.3 % and 7.3 % (n = 3). The limits of detection and quantitation were 3 and 10 ng/mL, respectively. The sensitivity of HPLC-UV for the determination of zolpidem was enhanced by electromembrane extraction. Finally, the method was employed for the quantitation of zolpidem in biological samples with relative recoveries in the range of 60-79 %.
- Full Text:
- Authors: Yaripour, Saeid , Mohammadi, Ali , Esfanjani, Isa , Walker, Roderick B , Nojavan, Saeed
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184723 , vital:44266 , xlink:href="http://dx.doi.org/10.17179/excli2018-1140"
- Description: In this study, for the first time, an electro-driven microextraction method named electromembrane extraction combined with a simple high performance liquid chromatography and ultraviolet detection was developed and validated for the quantitation of zolpidem in biological samples. Parameters influencing electromembrane extraction were evaluated and optimized. The membrane consisted of 2-ethylhexanol immobilized in the pores of a hollow fiber. As a driving force, a 150 V electric field was applied to facilitate the analyte migration from the sample matrix to an acceptor solution through a supported liquid membrane. The pHs of donor and acceptor solutions were optimized to 6.0 and 2.0, respectively. The enrichment factor was obtained >75 within 15 minutes. The effect of carbon nanotubes (as solid nano-sorbents) on the membrane performance and EME efficiency was evaluated. The method was linear over the range of 10-1000 ng/mL for zolpidem (R2 >0.9991) with repeatability (%RSD) between 0.3 % and 7.3 % (n = 3). The limits of detection and quantitation were 3 and 10 ng/mL, respectively. The sensitivity of HPLC-UV for the determination of zolpidem was enhanced by electromembrane extraction. Finally, the method was employed for the quantitation of zolpidem in biological samples with relative recoveries in the range of 60-79 %.
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The relative importance of autochthony along the longitudinal gradient of a small South African river influenced by agricultural activities
- Moyo, Sydney, Richoux, Nicole B
- Authors: Moyo, Sydney , Richoux, Nicole B
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454392 , vital:75340 , xlink:href="https://doi.org/10.1016/j.fooweb.2018.e00082"
- Description: Generalisations about the sources of organic matter that support aquatic consumers are usually focussed on certain parts of the world (particularly the northern hemisphere) and large rivers, and therefore may not include the full spectrum of food webs that occur in the southern hemisphere (particularly those with high nitrogen inputs). We studied the relative importance of organic matter sources to macroinvertebrate consumers in a small South African river. Based on previous observations of our system of interest and other agricultural streams, we hypothesised that (a) the carbon fuelling consumers is primarily derived from autochthonous (in situ) food sources regardless of sampling time and, (b) the contribution of autochthonous basal resources to consumers increases in importance as the river widens (from upper to downstream reaches). To test these predictions, stable carbon (δ13C) and nitrogen (δ15N) isotopes were used to estimate the contributions of local algal and land-based production to aquatic macroinvertebrates over space (six sites) and time (four sampling occasions between November 2012 and September 2013) along the Kowie River, South Africa. Mixing models revealed that consumers in the upper reaches assimilated terrestrially-derived allochthonous organic matter, and consumers in the middle and lower reaches assimilated primarily autochthonous basal resources (macrophytes and algae). The isotopic values of consumers and their food sources changed over time, indicating that food sources and consumers should be analysed many times throughout the year to capture that variability and ensure that ephemeral components of the food web are not missed. Our results enhance the growing body of literature on the dynamics of riverine systems and indicate the importance of autochthony in a small temperate river with high nitrogen inputs.
- Full Text:
- Authors: Moyo, Sydney , Richoux, Nicole B
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454392 , vital:75340 , xlink:href="https://doi.org/10.1016/j.fooweb.2018.e00082"
- Description: Generalisations about the sources of organic matter that support aquatic consumers are usually focussed on certain parts of the world (particularly the northern hemisphere) and large rivers, and therefore may not include the full spectrum of food webs that occur in the southern hemisphere (particularly those with high nitrogen inputs). We studied the relative importance of organic matter sources to macroinvertebrate consumers in a small South African river. Based on previous observations of our system of interest and other agricultural streams, we hypothesised that (a) the carbon fuelling consumers is primarily derived from autochthonous (in situ) food sources regardless of sampling time and, (b) the contribution of autochthonous basal resources to consumers increases in importance as the river widens (from upper to downstream reaches). To test these predictions, stable carbon (δ13C) and nitrogen (δ15N) isotopes were used to estimate the contributions of local algal and land-based production to aquatic macroinvertebrates over space (six sites) and time (four sampling occasions between November 2012 and September 2013) along the Kowie River, South Africa. Mixing models revealed that consumers in the upper reaches assimilated terrestrially-derived allochthonous organic matter, and consumers in the middle and lower reaches assimilated primarily autochthonous basal resources (macrophytes and algae). The isotopic values of consumers and their food sources changed over time, indicating that food sources and consumers should be analysed many times throughout the year to capture that variability and ensure that ephemeral components of the food web are not missed. Our results enhance the growing body of literature on the dynamics of riverine systems and indicate the importance of autochthony in a small temperate river with high nitrogen inputs.
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The status and distribution of a newly identified endemic galaxiid in the eastern Cape Fold Ecoregion, of South Africa
- Chakona, Gamuchirai, Swartz, Ernst R, Chakona, Albert
- Authors: Chakona, Gamuchirai , Swartz, Ernst R , Chakona, Albert
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453238 , vital:75233 , xlink:href="https://doi.org/10.1002/aqc.2850"
- Description: DNA-based studies have uncovered cryptic species and lineages within almost all freshwater fishes studied thus far from the Cape Fold Ecoregion (CFE) of South Africa. These studies have changed the way the CFE is viewed, as almost all stream fishes that were previously consid-ered to be of low conservation priority, because they were perceived to have broad geographical ranges, con-tain multiple historically isolated lineages, many of which are narrow-range endemics.
- Full Text:
- Authors: Chakona, Gamuchirai , Swartz, Ernst R , Chakona, Albert
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453238 , vital:75233 , xlink:href="https://doi.org/10.1002/aqc.2850"
- Description: DNA-based studies have uncovered cryptic species and lineages within almost all freshwater fishes studied thus far from the Cape Fold Ecoregion (CFE) of South Africa. These studies have changed the way the CFE is viewed, as almost all stream fishes that were previously consid-ered to be of low conservation priority, because they were perceived to have broad geographical ranges, con-tain multiple historically isolated lineages, many of which are narrow-range endemics.
- Full Text:
The status and distribution of a newly identified endemic galaxiid in the eastern Cape Fold Ecoregion, of South Africa
- Chakona, Gamuchirai, Swartz, Ernst R, Chakona, Albert
- Authors: Chakona, Gamuchirai , Swartz, Ernst R , Chakona, Albert
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425492 , vital:72250 , xlink:href="https://doi.org/10.1002/aqc.2850"
- Description: DNA-based studies have uncovered cryptic species and lineages within almost all freshwater fishes studied thus far from the Cape Fold Ecoregion (CFE) of South Africa. These studies have changed the way the CFE is viewed, as almost all stream fishes that were previously consid-ered to be of low conservation priority, because they were perceived to have broad geographical ranges, con-tain multiple historically isolated lineages, many of which are narrow-range endemics.
- Full Text:
- Authors: Chakona, Gamuchirai , Swartz, Ernst R , Chakona, Albert
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425492 , vital:72250 , xlink:href="https://doi.org/10.1002/aqc.2850"
- Description: DNA-based studies have uncovered cryptic species and lineages within almost all freshwater fishes studied thus far from the Cape Fold Ecoregion (CFE) of South Africa. These studies have changed the way the CFE is viewed, as almost all stream fishes that were previously consid-ered to be of low conservation priority, because they were perceived to have broad geographical ranges, con-tain multiple historically isolated lineages, many of which are narrow-range endemics.
- Full Text:
Think Piece: Pioneers as relational subjects? Probing relationality as phenomenon shaping collective learning and change agency formation
- Authors: Lotz-Sisitka, Heila
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182787 , vital:43874 , xlink:href="DOI 10.4314/sajee.v34i1.5"
- Description: This paper deliberates on how relationality is framed in collective learning and change agency formation processes, with an emphasis on green economy and renewable energy learning contexts. The paper is not focused on empirical analysis of relationality in collective learning, but rather probes the phenomenon in order to provide more carefully constituted theoretical and analytical tools for further empirical research. The paper uses references to South African and Danish cases (albeit in slightly different ways), and, through this, it sets out to provide tools for generative insights and research into a recent international policy and strategy process which is bringing national-level Green Economy Learning Assessments (GELA) into being, including one in South Africa. Central to these GELAs is the notion of participatory or relational competence, which appears to be a central feature of collective learning, although this is not empirically analysed in this paper. In case study work undertaken for the GELA in South Africa that focused on South Africa’s major renewable energy development, and in the Samsø Island renewable energy transition case in Denmark, this competence appeared to come into focus in praxis. Interestingly, however, it appeared to come into focus colloquially as a discourse on ‘pioneers’ or ‘champions’, a phenomenon noticed in both the South African and Danish contexts. This paper probes this phenomenon further, especially since it initially appears to be contradictory to the emphasis on participatory and relational competence in the GELA study framework. This is because the concept of ‘pioneer/champion’ appears to highlight individual capabilities rather than collective, relational competences. Yet, on closer inspection, it is indeed the relational competences of the pioneer/champion, who is constituted as a ‘relational subject’ with a key role to play in producing shared relational goods, that appears to be significant to the collective learning and action process. This, as argued in the paper, requires a differentiation of relationism and relational realism. This Think Piece, which thinks with both theory and praxis, therefore offers a possible framework for more detailed empirical studies on relationality in collective learning and change agency formation.
- Full Text:
- Authors: Lotz-Sisitka, Heila
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182787 , vital:43874 , xlink:href="DOI 10.4314/sajee.v34i1.5"
- Description: This paper deliberates on how relationality is framed in collective learning and change agency formation processes, with an emphasis on green economy and renewable energy learning contexts. The paper is not focused on empirical analysis of relationality in collective learning, but rather probes the phenomenon in order to provide more carefully constituted theoretical and analytical tools for further empirical research. The paper uses references to South African and Danish cases (albeit in slightly different ways), and, through this, it sets out to provide tools for generative insights and research into a recent international policy and strategy process which is bringing national-level Green Economy Learning Assessments (GELA) into being, including one in South Africa. Central to these GELAs is the notion of participatory or relational competence, which appears to be a central feature of collective learning, although this is not empirically analysed in this paper. In case study work undertaken for the GELA in South Africa that focused on South Africa’s major renewable energy development, and in the Samsø Island renewable energy transition case in Denmark, this competence appeared to come into focus in praxis. Interestingly, however, it appeared to come into focus colloquially as a discourse on ‘pioneers’ or ‘champions’, a phenomenon noticed in both the South African and Danish contexts. This paper probes this phenomenon further, especially since it initially appears to be contradictory to the emphasis on participatory and relational competence in the GELA study framework. This is because the concept of ‘pioneer/champion’ appears to highlight individual capabilities rather than collective, relational competences. Yet, on closer inspection, it is indeed the relational competences of the pioneer/champion, who is constituted as a ‘relational subject’ with a key role to play in producing shared relational goods, that appears to be significant to the collective learning and action process. This, as argued in the paper, requires a differentiation of relationism and relational realism. This Think Piece, which thinks with both theory and praxis, therefore offers a possible framework for more detailed empirical studies on relationality in collective learning and change agency formation.
- Full Text:
Transforming while transferring: An exploratory study of how transferability of skills is key in the transformation of higher education
- Bazana, Sandiso, McLaren, Logan, Kabungaidze, Trust
- Authors: Bazana, Sandiso , McLaren, Logan , Kabungaidze, Trust
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453793 , vital:75286 , xlink:href="https://hdl.handle.net/10520/EJC-102f9d32bf"
- Description: The importance of skills within the transformation of higher education is a crucial factor that has been insufficiently considered. Transformation in terms of higher education forms a fundamental part of the post-apartheid South African society. This transformation movement seems to exclude the possible role and contributions of the older generation of academics. Using a social constructionist viewpoint, this qualitative study sought to bring to the debate of transformation of higher education the important question of skills transferability between older generation academics and the new generation. From interviewing five retired white academics, the study found that institutional culture and implementation of labour legislation through the Human Resources department by the university in question affect the transferability of skills and that proper programmes of voluntary mentorship should be put in place as to allow the growth of both the older generation and new generation academics. The use of new generation academics’ perspectives could yield more results and findings that can further this area of study, as well as allow a more diverse and richer understanding of the perception of skills transferability within the transformation of higher education institutions. This further understanding for research is needed to emphasise the importance of knowledge production through the integration of both young academics’ as well as older academics’ perspectives. This is to be achieved by engaging with other universities and academics, so that a broader analysis of skills transferability within higher education can be understood.
- Full Text:
- Authors: Bazana, Sandiso , McLaren, Logan , Kabungaidze, Trust
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453793 , vital:75286 , xlink:href="https://hdl.handle.net/10520/EJC-102f9d32bf"
- Description: The importance of skills within the transformation of higher education is a crucial factor that has been insufficiently considered. Transformation in terms of higher education forms a fundamental part of the post-apartheid South African society. This transformation movement seems to exclude the possible role and contributions of the older generation of academics. Using a social constructionist viewpoint, this qualitative study sought to bring to the debate of transformation of higher education the important question of skills transferability between older generation academics and the new generation. From interviewing five retired white academics, the study found that institutional culture and implementation of labour legislation through the Human Resources department by the university in question affect the transferability of skills and that proper programmes of voluntary mentorship should be put in place as to allow the growth of both the older generation and new generation academics. The use of new generation academics’ perspectives could yield more results and findings that can further this area of study, as well as allow a more diverse and richer understanding of the perception of skills transferability within the transformation of higher education institutions. This further understanding for research is needed to emphasise the importance of knowledge production through the integration of both young academics’ as well as older academics’ perspectives. This is to be achieved by engaging with other universities and academics, so that a broader analysis of skills transferability within higher education can be understood.
- Full Text:
Trophic ecology of adult male O donata. II. D ietary contributions of aquatic food sources
- Chari, Lenin D, Moyo, Sydney, Richoux, Nicole B
- Authors: Chari, Lenin D , Moyo, Sydney , Richoux, Nicole B
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456403 , vital:75510 , xlink:href="https://doi.org/10.1111/een.12459"
- Description: 1. Insects that emerge from rivers provide nutritional subsidies to local riparian predators. Adult damselflies and dragonflies often benefit from aquatic resources, but their high mobility and evasiveness have made it difficult to monitor their diets. 2. A dual fatty acid and stable isotope analysis approach was used to investigate the links between Odonata size and behaviour with proportions of their aquatically derived nutri-tional sources. Additionally, the study investigated the variation in die-tary contributions of aquatic food sources to Odonata between two sec-tions of a river, each with different aquatic productivity rates. 3. Varia-tions in body size and foraging method of Odonata in the Kowie River (South Africa) contributed to differences in the contributions of aquatic food sources to their diets. Large Odonata that consumed prey in flight had smaller proportions of aquatic indicator fatty acids and stable iso-tope‐generated proportions of aquatic food sources than did the smaller Odonata that consumed prey from perches. 4. There was a considera-ble amount of interspecific variation in indicators of aquatic feeding, but Odonata at an upstream site had smaller proportions of aquatic indica-tors than those at a downstream site which had higher insect emer-gence rates. 5. The findings of this study contribute information on the dynamics of feeding ecology among adult Odonata, and the substantial contributions of aquatic prey (>80% of total diet in some cases) indicat-ed that cross‐boundary trophic linkages via odonates are strong in the Kowie River.
- Full Text:
- Authors: Chari, Lenin D , Moyo, Sydney , Richoux, Nicole B
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/456403 , vital:75510 , xlink:href="https://doi.org/10.1111/een.12459"
- Description: 1. Insects that emerge from rivers provide nutritional subsidies to local riparian predators. Adult damselflies and dragonflies often benefit from aquatic resources, but their high mobility and evasiveness have made it difficult to monitor their diets. 2. A dual fatty acid and stable isotope analysis approach was used to investigate the links between Odonata size and behaviour with proportions of their aquatically derived nutri-tional sources. Additionally, the study investigated the variation in die-tary contributions of aquatic food sources to Odonata between two sec-tions of a river, each with different aquatic productivity rates. 3. Varia-tions in body size and foraging method of Odonata in the Kowie River (South Africa) contributed to differences in the contributions of aquatic food sources to their diets. Large Odonata that consumed prey in flight had smaller proportions of aquatic indicator fatty acids and stable iso-tope‐generated proportions of aquatic food sources than did the smaller Odonata that consumed prey from perches. 4. There was a considera-ble amount of interspecific variation in indicators of aquatic feeding, but Odonata at an upstream site had smaller proportions of aquatic indica-tors than those at a downstream site which had higher insect emer-gence rates. 5. The findings of this study contribute information on the dynamics of feeding ecology among adult Odonata, and the substantial contributions of aquatic prey (>80% of total diet in some cases) indicat-ed that cross‐boundary trophic linkages via odonates are strong in the Kowie River.
- Full Text:
Urban street names: An opportunity to examine biocultural relationships?
- Authors: Shackleton, Charlie M
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182285 , vital:43817 , xlink:href="https://doi.org/10.1371/journal.pone.0200891"
- Description: With increasing urbanisation there is concern regarding loss of experience and knowledge of biodiversity amongst urban populations. Yet biodiversity representations are retained in many art and functional forms, including names of places, buildings, institutions and streets. These manifestations offer a window to examine the relationship between humans and their experienced or imagined environment using a biocultural lens. I quantified the current prevalence of urban streets named after animals or plant species, the diversity of species represented, whether they are native or non-native, whether representative of the biome in which the town was situated and the change in prevalence through time. The street names of 48 towns in a one degree wide south-north belt across seven of South African’s biomes were captured and analysed. Of the 4,359 street names, 11.1% were named after plants (218 species) and 5.3% after animals (131 species), although some towns had none and others more than 40%. Approximately half of the plants were native to South Africa, whereas over 80% of the animals were. There was no correspondence between the species composition reflected in street names and the biome in which towns were located. The proportion of streets named after plants or animals has generally increased over the last two hundred years. These results provide insights into the bioculturally defined plants and animals that are valued by past and present urban communities, showing that they are generally from a wider array than can be found or experienced in the local setting.
- Full Text:
- Authors: Shackleton, Charlie M
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182285 , vital:43817 , xlink:href="https://doi.org/10.1371/journal.pone.0200891"
- Description: With increasing urbanisation there is concern regarding loss of experience and knowledge of biodiversity amongst urban populations. Yet biodiversity representations are retained in many art and functional forms, including names of places, buildings, institutions and streets. These manifestations offer a window to examine the relationship between humans and their experienced or imagined environment using a biocultural lens. I quantified the current prevalence of urban streets named after animals or plant species, the diversity of species represented, whether they are native or non-native, whether representative of the biome in which the town was situated and the change in prevalence through time. The street names of 48 towns in a one degree wide south-north belt across seven of South African’s biomes were captured and analysed. Of the 4,359 street names, 11.1% were named after plants (218 species) and 5.3% after animals (131 species), although some towns had none and others more than 40%. Approximately half of the plants were native to South Africa, whereas over 80% of the animals were. There was no correspondence between the species composition reflected in street names and the biome in which towns were located. The proportion of streets named after plants or animals has generally increased over the last two hundred years. These results provide insights into the bioculturally defined plants and animals that are valued by past and present urban communities, showing that they are generally from a wider array than can be found or experienced in the local setting.
- Full Text:
4-Bis (4-aminophenoxy) phenoxy derivitized phthalocyanine conjugated to metallic nanoparticles
- Nwaji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188965 , vital:44802 , xlink:href="https://doi.org/10.1039/C7NJ02718D"
- Description: In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of 4-(2,4-bis(4-aminophenoxy)phenoxy) phthalocyinato zinc(II) phthalocyanine (6) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques using 532 nm nanosecond pulses. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibit higher excited state absorption cross-section compared to ground state absorption. Enhanced optical limiting performance was observed when complex 6 was conjugated to nanoparticles with 6CB-AuNPs (CB = covalent bond) showing the highest optical limiting threshold of 0.36 J cm−2.
- Full Text:
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188965 , vital:44802 , xlink:href="https://doi.org/10.1039/C7NJ02718D"
- Description: In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of 4-(2,4-bis(4-aminophenoxy)phenoxy) phthalocyinato zinc(II) phthalocyanine (6) conjugated to metallic nanoparticles have been investigated using open aperture Z-scan techniques using 532 nm nanosecond pulses. The nonlinear optical response demonstrated that the studied complex and the nanoconjugates exhibit higher excited state absorption cross-section compared to ground state absorption. Enhanced optical limiting performance was observed when complex 6 was conjugated to nanoparticles with 6CB-AuNPs (CB = covalent bond) showing the highest optical limiting threshold of 0.36 J cm−2.
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Breaking the silence on abortion: the role of adult community abortion education in fostering resistance to norms
- Bloomer, Fiona, O'Dowd, Kellie, Macleod, Catriona I
- Authors: Bloomer, Fiona , O'Dowd, Kellie , Macleod, Catriona I
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444250 , vital:74210 , xlink:href="https://doi.org/10.1080/13691058.2016.1257740"
- Description: Meanings of abortion in society are constructed within sociohistorical and gendered spaces and manifested through myriad discourses that impact on the perception and treatment of the issue in that society. In societies with powerful oppressive anti-abortion norms, such as Northern Ireland, little is known as to how these norms are resisted by the adult population. This study uses a Foucauldian feminist approach to show how resistance to religious and patriarchal norms can be fostered through adult community abortion education. This resistance is multi-faceted and bolstered by a lived experience discourse, which does not necessarily involve eschewing religious notions held within society.
- Full Text:
- Authors: Bloomer, Fiona , O'Dowd, Kellie , Macleod, Catriona I
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444250 , vital:74210 , xlink:href="https://doi.org/10.1080/13691058.2016.1257740"
- Description: Meanings of abortion in society are constructed within sociohistorical and gendered spaces and manifested through myriad discourses that impact on the perception and treatment of the issue in that society. In societies with powerful oppressive anti-abortion norms, such as Northern Ireland, little is known as to how these norms are resisted by the adult population. This study uses a Foucauldian feminist approach to show how resistance to religious and patriarchal norms can be fostered through adult community abortion education. This resistance is multi-faceted and bolstered by a lived experience discourse, which does not necessarily involve eschewing religious notions held within society.
- Full Text:
Effects of substituents on the electrocatalytic activity of cobalt phthalocyanines when conjugated to graphene quantum dots
- Centane, Sixolile, Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Centane, Sixolile , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188237 , vital:44737 , xlink:href="https://doi.org/10.1002/elan.201700252"
- Description: We report on the π–π interactions between graphene quantum dots (GQDs) and the following cobalt phthalocyanine derivatives: cobalt monocarboxyphenoxy phthalocyanine (complex 1), cobalt tetracarboxyphenoxyphthalocyanine (complex 2), and cobalt tetraaminophenoxy phthalocyanine (complex 3). The conjugates (conj) with GQDs are represented as 1@GQDs(conj), 2@GQDs(conj) and 3@GQDs(conj), respectively. The resulting phthalocyanine/GQDs conjugates were adsorbed on containing a glassy carbon electrode (GCE) using the drop and dry method. We explore the electrochemical properties of phthalocyanines functionalized with both electron withdrawing groups and electron donating groups when non-covalently linked to the π-electron rich graphene quantum dots. GCE/3, GCE/2@GQDs(conj) and GCE/1@GQDs(conj) had the lowest limits of detection (LOD). Sequentially modified electrodes showed less favourable detection limits compared to the conjugates.
- Full Text:
- Authors: Centane, Sixolile , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188237 , vital:44737 , xlink:href="https://doi.org/10.1002/elan.201700252"
- Description: We report on the π–π interactions between graphene quantum dots (GQDs) and the following cobalt phthalocyanine derivatives: cobalt monocarboxyphenoxy phthalocyanine (complex 1), cobalt tetracarboxyphenoxyphthalocyanine (complex 2), and cobalt tetraaminophenoxy phthalocyanine (complex 3). The conjugates (conj) with GQDs are represented as 1@GQDs(conj), 2@GQDs(conj) and 3@GQDs(conj), respectively. The resulting phthalocyanine/GQDs conjugates were adsorbed on containing a glassy carbon electrode (GCE) using the drop and dry method. We explore the electrochemical properties of phthalocyanines functionalized with both electron withdrawing groups and electron donating groups when non-covalently linked to the π-electron rich graphene quantum dots. GCE/3, GCE/2@GQDs(conj) and GCE/1@GQDs(conj) had the lowest limits of detection (LOD). Sequentially modified electrodes showed less favourable detection limits compared to the conjugates.
- Full Text:
Graphene quantum dots anchored onto mercaptopyridine-substituted zinc phthalocyanine-Au@ Ag nanoparticle hybrid: Application as fluorescence “off-on-off” sensor for Hg2+ and biothiols
- Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188194 , vital:44731 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.06.002"
- Description: Novel supramolecular hybrid containing polyethyleneimine-functionalized graphene quantum dots (PEI-GQDs) and mercaptopyridine-substituted zinc phthalocyanine (Pc)-Au@Ag nano-alloys is presented in this study. The designed hybrid was employed as a dual fluorescence nanoprobe for Hg2+ and biothiol detection in aqueous solution using PEI-GQDs as the fluorescence switching signal probe. The dual sensing platform for the analytes detection is firstly, based on the quenching (turn “OFF”) of the PEI-GQDs fluorescence upon π-π interaction or electrostatic attraction with Pc-Au@Ag conjugate. The quenched fluorescence can be switched back to the “ON” mode in the presence of Hg2+ and switched “OFF” again when biothiols are introduced to capture the Hg2+ ion via the formation of the strong metal-thiol bond (Hg-S). The “off-on-off” processes were modulated by different amounts of Hg2+ and biothiols. The nanoprobes were found to be highly stable and selective towards the target analytes in the presence of other amino acids and metal ions. Also, the probes were successfully deployed in the assay of the test analytes in spiked samples.
- Full Text:
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188194 , vital:44731 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.06.002"
- Description: Novel supramolecular hybrid containing polyethyleneimine-functionalized graphene quantum dots (PEI-GQDs) and mercaptopyridine-substituted zinc phthalocyanine (Pc)-Au@Ag nano-alloys is presented in this study. The designed hybrid was employed as a dual fluorescence nanoprobe for Hg2+ and biothiol detection in aqueous solution using PEI-GQDs as the fluorescence switching signal probe. The dual sensing platform for the analytes detection is firstly, based on the quenching (turn “OFF”) of the PEI-GQDs fluorescence upon π-π interaction or electrostatic attraction with Pc-Au@Ag conjugate. The quenched fluorescence can be switched back to the “ON” mode in the presence of Hg2+ and switched “OFF” again when biothiols are introduced to capture the Hg2+ ion via the formation of the strong metal-thiol bond (Hg-S). The “off-on-off” processes were modulated by different amounts of Hg2+ and biothiols. The nanoprobes were found to be highly stable and selective towards the target analytes in the presence of other amino acids and metal ions. Also, the probes were successfully deployed in the assay of the test analytes in spiked samples.
- Full Text:
Halogen substituted A2B type Co (III) triarylcorroles
- Niu, Yingjie, Li, Minzhi, Zhang, Qianchong, Zhu, Weihua, Mack, John, Fomo, Gertrude, Nyokong, Tebello, Liang, Xu
- Authors: Niu, Yingjie , Li, Minzhi , Zhang, Qianchong , Zhu, Weihua , Mack, John , Fomo, Gertrude , Nyokong, Tebello , Liang, Xu
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233048 , vital:50051 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.02.049"
- Description: Seven low symmetry A2B type Co(III)triarylcorroles with electron withdrawing meso-aryl substituents have been synthesized and characterized. A detailed analysis of the optical and redox properties has been carried out by comparing their optical spectroscopy, electrochemistry and spectroelectrochemistry to trends predicted in a series of DFT and TD-DFT calculations. The results demonstrate that Co(III)corroles are highly effective catalysts for hydrogen evolution reactions (HERs). Moreover, there is a marked enhancement in their homogenous catalytic ability when halogen atoms are introduced at the B position, which demonstrates that facile modifying the meso-aryl rings is a effective strategy for developing new HER catalysts. The electrochemical results demonstrate that an unusual two step modulation of HER reactions can be achieved by using singly and doubly electrochemical reduced cobalt triarylcorroles anions.
- Full Text:
- Authors: Niu, Yingjie , Li, Minzhi , Zhang, Qianchong , Zhu, Weihua , Mack, John , Fomo, Gertrude , Nyokong, Tebello , Liang, Xu
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233048 , vital:50051 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.02.049"
- Description: Seven low symmetry A2B type Co(III)triarylcorroles with electron withdrawing meso-aryl substituents have been synthesized and characterized. A detailed analysis of the optical and redox properties has been carried out by comparing their optical spectroscopy, electrochemistry and spectroelectrochemistry to trends predicted in a series of DFT and TD-DFT calculations. The results demonstrate that Co(III)corroles are highly effective catalysts for hydrogen evolution reactions (HERs). Moreover, there is a marked enhancement in their homogenous catalytic ability when halogen atoms are introduced at the B position, which demonstrates that facile modifying the meso-aryl rings is a effective strategy for developing new HER catalysts. The electrochemical results demonstrate that an unusual two step modulation of HER reactions can be achieved by using singly and doubly electrochemical reduced cobalt triarylcorroles anions.
- Full Text:
Laser induced photodegradation of Orange G using phthalocyanine–cobalt ferrite magnetic nanoparticle conjugates electrospun in polystyrene nanofibers
- Mapukata, Sivuyisiwe, Chindeka, Francis, Sekhosana, Kutloano E, Nyokong, Tebello
- Authors: Mapukata, Sivuyisiwe , Chindeka, Francis , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188617 , vital:44769 , xlink:href="https://doi.org/10.1016/j.mcat.2017.06.028"
- Description: Conjugates of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc) and zinc tetraaminophenoxy phthalocyanine (ZnTAPPc) with amine and carboxyl functionalised cobalt ferrite magnetic nanoparticles (CoFe2O4 MNPs), respectively were electrospun into polystyrene (PS) fibers. The resulting composites; ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were compared based on their photophysical properties and photocatalytic efficiencies in degrading Orange G (OG) using laser as the photoexcitation source. The photocatalytic efficiencies of ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were compared based on them having different lengths in the linkage chains between the Pcs and CoFe2O4 MNPs and different sizes. Covalent linkage of the Pcs to the CoFe2O4 MNPs enhanced the singlet oxygen and reactive oxygen species (ROS) production of the Pcs and CoFe2O4, respectively hence ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were found to be more effective photocatalysts than their respective Pcs and CoFe2O4 MNPs. Moreover, the kinetic analyses of the photodecomposition of OG showed that the degradation was in agreement with both pseudo-first order kinetics and followed the Langmuir–Hinshelwood model.
- Full Text:
- Authors: Mapukata, Sivuyisiwe , Chindeka, Francis , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188617 , vital:44769 , xlink:href="https://doi.org/10.1016/j.mcat.2017.06.028"
- Description: Conjugates of zinc tetracarboxyphenoxy phthalocyanine (ZnTCPPc) and zinc tetraaminophenoxy phthalocyanine (ZnTAPPc) with amine and carboxyl functionalised cobalt ferrite magnetic nanoparticles (CoFe2O4 MNPs), respectively were electrospun into polystyrene (PS) fibers. The resulting composites; ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were compared based on their photophysical properties and photocatalytic efficiencies in degrading Orange G (OG) using laser as the photoexcitation source. The photocatalytic efficiencies of ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were compared based on them having different lengths in the linkage chains between the Pcs and CoFe2O4 MNPs and different sizes. Covalent linkage of the Pcs to the CoFe2O4 MNPs enhanced the singlet oxygen and reactive oxygen species (ROS) production of the Pcs and CoFe2O4, respectively hence ZnTCPPc-CoFe2O4/PS and ZnTAPPc-CoFe2O4/PS were found to be more effective photocatalysts than their respective Pcs and CoFe2O4 MNPs. Moreover, the kinetic analyses of the photodecomposition of OG showed that the degradation was in agreement with both pseudo-first order kinetics and followed the Langmuir–Hinshelwood model.
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